1. Field of the Invention
The present invention relates to an imaging device that allows focus detection based on a contrast detection method and focus detection based on a phase difference detection method.
2. Description of the Related Art
In general, imaging devices such as digital single lens reflex (SLR) cameras perform focus detection based on a phase difference detection method (phase difference AF) using phase difference AF sensors to perform auto-focus control (AF control). Phase difference AF has an advantage of quicker focus detection than focus detection based on a contrast detection method (contrast AF) in which a position of a focus lens at which image signals obtained by an imaging element have a peak level of contrast is detected although it has a drawback of lower focus detection accuracy than contrast AF.
An AF method having the advantages of both phase difference AF and contrast AF, called a hybrid AF method, has been proposed. For example, Japanese Unexamined Patent Application Publication No. 2003-7994 discloses an imaging element capable of obtaining two images at the same time for detecting a phase difference. With the use of such an imaging element, the hybrid AF method can be achieved.
In the hybrid AF method, for example, a focus lens is quickly driven to an in-focus position detected by the phase difference AF method and then the contrast AF method is enabled to perform high-precision focus detection. Thus, AF control having the advantages of both AF methods is realized.